3M VHB Tape

[Hdlaut]

Originally Posted by rickst29

and can be mounted with only 4 Z-bars. It also weight far less, your bigger panel could create a lifting issue.

Are you looking the front shell or the rear shell? For the case of the rear shell, the remaining "depth" when closed is very important and varies according to the model of TM you have.

Oh. Rats. Something else I didn't consider. It would be installed on the rear shell of a 2006 3023.

[jagizzi]

I installed a 400W panel on the rear of our 2005 2720 using Z-brackets. I had to add additional aluminum spacers to allow clearance for the crown in the roof. The spacers were simply aluminum square extrusions.

The panel weighs 40#. I could still open and close the shell but elected to change out the torsion bars to the next larger size as they were fully adjusted to the max, and it was difficult to open. I am pretty sure that it would have gotten more difficult over time, hence the change out.

FWIW, and I differ from some on this, I firmly believe in backing up critical connections with a mechanical fastener. Failures happen, and I don't want my VHB tape attached panel to go sailing while I am traveling. The extrusions are through bolted to the roof with fender washers inside. The holes are sealed, at the roof, with 3M UV4000 and then the extrusions are also bedded in the stuff. There is no sealant in the screw hole itself nor inside at the ceiling. If there is a leak, and I don't expect it, I want to know it; and I will as it will drip on the bed ;-)

This setup has exceeded my expectations from a performance standpoint. I have gotten more than 30A into the batteries on many occasions and when the sun is available am always able to make up night time usage of my CPAP and the fridge.

[rickst29]

The ratio of watts per pound is really good, and a panel iike his will fit on the rear of anything '2720 or larger'.

Panels of this size are set up with two mounting holes along each long edge, and those holes are not near the corners - like Jim's photo, they usually have about 15% overhang towards the short sides and only 60% of total length between the mounts. That allows for 4 mount points (rather than 6) to be more than sufficient.

On a normal roof installation, a single long pair of horizontal rails is use to mount multiple panels in a vertical orientation. I agree with Jim that a panel that heavy, using just 4 Z-bars, needs to have the Z-Bars held through the roof with SS screws and interior washer/bolts (not just VHB tape). Jim's additional use of VHB between the between the Z-bar and the roof further improves adherence and water resistance. With screws, the screws themselves and the washers on the inslde ceiling can be also be set against the celing with 3M 4200 boat sealant, providing another seal from the inside as well.

- - -
But, as Jim found, all the extra weight might require a torsion bar upgrade (rather than a mere adjustment). The panels themselves are also to big for Fedex/UPS. To avoid paying csotly truck freight, you will instead want to attempt purchasing a single "left over" from a local company which specializes in home installations. (The buy entire truckloads or pallets at a time, and often have a few "left over panels" from those bulk purchases.

[Hdlaut]

Great info @jagizzi ! I could have bought a 400W panel when I purchased this one. However, I hadn't measured first - dumb - and the 335W seemed like it should be fine. Looking at your 400W panel gives me confidence I'll be able to fit mine.

Torsion bars. Ugh. Another item I didn't consider! Were you able to just order them from the factory, and did the shipping cost almost as much as the bars?

I will be installing a 280AH lifepo4 battery and a 2000W Victron Multiplus inverter / charger. My goal is to remove the old gas range and install an induction cooktop and a microwave. For the limited cooking usage it should work out. And in the hot CA summers, the additional cooking heat will be much less.

I've already replaced the 12V battery at the front of the trailer with a 100Ah lifepo4 battery to use for the existing 12V loads.

[rickst29]

On the front shell of my own 2619, I have 4*100 "skinny" flexible panels mounted front to back, with 2 "street side" and 2 "curb side" of the center seam of the shell.

That would be very high power and avoid the issue of "too much weight", creating three other issues instead:

(1) Although I have never had a 'flex panel' panel (except for one case an accident ripping the top-mounted connector right off), they are generally less reliable and durable.

(2) If hit by hail, they would almost certainly be damaged. (Mine have been subjected only to heavy rains and light snow.)

(3) They transmit a lot of heat into the surface of the roof. (Glass panels are mounted above the roof, allowing an inch of air space fopr wind to carry away the heat).

- - -
You would need to have at least 47" of remaining length when the shells are closed - or you could switch to mounting on the front roof, as I did. That was this panel, which costs less on sale: https://www.ebay.com/itm/145103635981

[Hdlaut]

Thanks rickst29. Good input and confirmation regarding thru-bolting and mount spacing.

I bought the brand new Panasonic panel locally for $100 from a guy who gets them from a friend who is a large distributor with leftovers. I helped my son purchase 4.8KW - 12 panels - from the same guy last year for $2k.

[Hdlaut]

I had a boat w/ 3-330W panels previously and when I bought it used, it already had flexible panels installed. They were DOA after 5 years. So when I replaced them, I went with glass panels.

Having said that, that was 14 years ago (when they were originally installed) and I believe they are much better now. Further, the marine environment can and will destroy anything.

[Wavery]

Technical data sheet for 3M 4941 VHB Tape:

https://technicaldatasheets.3m.com/en_US?pif=000062

Shear strength is 70# per sq inch. Typical Z-bracket length 4", Width 1". 4sq" = 280# of shear strength per bracket x 4 brackets = 1,120 # of shear strength and 1,460# of tensile strength.

[Wavery]

Originally Posted by Hdlaut

Thanks rickst29. Good input and confirmation regarding thru-bolting and mount spacing.

I bought the brand new Panasonic panel locally for $100 from a guy who gets them from a friend who is a large distributor with leftovers. I helped my son purchase 4.8KW - 12 panels - from the same guy last year for $2k.

I would highly recommend NOT drilling through the TM roof. If you decide to do that, be sure to insert 1" long crush spacers in the roof for the bolts to go through and take all of the force of the compression when tightening the bolts. If you do not use crush spacers (sleeves), The vibration of driving down the road will cause the styrofoam in the roof to crush which will result in having to tighten the nuts farther to keep the panel secure against the roof. Over time, the roof may become severely crushed.

The square tube spacers are an excellent idea for raising the panel off the roof. However, instead of bolting the double tubes together, I would (again) recommend the VHB tape. If you double up those spacers and make them 6" long, you'd end up with 12 sq inches of surface contact with the roof (per leg). that would result in 48sq inches of VHB tape which would result in 3,360# of shear strength and 4,080# of tensile strength. That means that you could lift the entire TrailManor off the ground by the solar panel before that tape would separate.

[Hdlaut]

Originally Posted by Wavery

I would highly recommend NOT drilling through the TM roof. If you decide to do that, be sure to insert 1" long crush spacers in the roof for the bolts to go through and take all of the force of the compression when tightening the bolts. If you do not use crush spacers (sleeves), The vibration of driving down the road will cause the styrofoam in the roof to crush which will result in having to tighten the nuts farther to keep the panel secure against the roof. Over time, the roof may become severely crushed.

The square tube spacers are an excellent idea for raising the panel off the roof. However, instead of bolting the double tubes together, I would (again) recommend the VHB tape. If you double up those spacers and make them 6" long, you'd end up with 12 sq inches of surface contact with the roof (per leg). that would result in 48sq inches of VHB tape which would result in 3,360# of shear strength and 4,080# of tensile strength. That means that you could lift the entire TrailManor off the ground by the solar panel before that tape would separate.

Wow! Food for thought. This may be the best forum on the internet. Thanks!